Feb 1 (Reuters) - Constellation Brands Inc on Friday attacked the U.S. government's move to block Anheuser-Busch InBev's proposed $20.1 billion takeover of Mexican brewer Grupo Modelo. Constellation, which would become the sole U.S. distributor of Modelo beers like Corona and Negra Modelo through a related $1.85 billion transaction, said Thursday's action by the Department of Justice "demonstrates its incomplete understanding of the proposed transaction." The U.S. Department of Justice i